1. Field of the Invention
This invention relates generally to magnetic storage device operation and more particularly to a method and system for writing data to a magnetic storage device when the device ambient temperature is relatively cold or hot.
2. Description of the Prior Art
A common concern for saving data onto a magnetic storage device is the reliability of the write operation when performed at the extremes of the temperature specification. While the read operation works well under these extreme circumstances, the write process may result in unrecoverable hard errors when attempts are made to read the data on either the target block or blocks adjacent to the target block.
One source of the problems at the temperature extremes is the coercivity of the storage media, for instance, a magnetic disk or tape. The disk coercivity changes with temperature. In a cold-temperature environment, the disk coercivity is high, whereas in a warm-temperature environment, the disk coercivity is low. Hence, at the low temperatures the disk is more difficult to write; and at the warm temperatures, there is the potential of writing an extra wide track resulting in adjacent track squeeze. Therefore, on the one hand, when the disk coercivity is high in a low-temperature environment, the question is whether or not data will be saved onto the media and, if the data are saved, whether or not the data saved can be retrieved successfully. On the other hand, when the disk coercivity is low in a high-temperature environment, the question is whether or not the tracks adjacent to the target track still contain their original data after the write operation.
FIG. 1A is a diagram illustrating the effect of disk coercivity on the written data bit width (track width) when the device is operating at a normal ambient temperature. A magnetic recording head 10 is shown flying above a magnetic disk 12. Magnetic field 14 is generated by the recording head 10 when the head 10 is writing to the disk 12 and saves a recorded magnet (data bit) 16 on the disk media 12. The width of recorded magnet 16 stays within a particular range when the recording head writes to the disk 12 so long as the device ambient temperature is within a normal operating temperature range.
However, as depicted in FIG. 1B, the disk coercivity is lower when the device ambient temperature is warmer, and the recorded magnets 18 saved on the disk media under this circumstance are wider than the recorded magnets 16 written to the disk media under the normal operating temperature as shown in FIG. 1A.
Similarly, as illustrated in FIG. 1C, the disk coercivity is higher when the device ambient temperature is cooler, and the recorded magnets 20 stored on the disk media under this circumstance are narrower than the recorded magnets 16 saved onto the disk media under the normal operating temperature as shown in FIG. 1A.
FIGS. 2A through 2C are plan view diagrams showing the widths of the tracks written onto a disk under the various temperature regimes illustrated in FIGS. 1A through 1C. As shown in these diagrams, as the widths of the recorded magnetic data bits formed on the media change under different temperatures so do the track widths. FIG. 2A indicates three data tracks 22 each written under normal operating temperature. An arrow 24 shows the direction of magnetic head movement. Previously recorded data bits 28 are being written over with data to be saved in the current write operation. FIG. 2B shows a middle track 30 written at a higher temperature than the two surrounding tracks 22 which were written at normal operating temperature. As expected, the widths of the magnetic data bits in the middle track 30 are wider than those of the tracks written under normal operating temperatures. As a result, a track written under higher temperature may squeeze into its adjacent tracks and may destroy the data previously recorded thereon. For a save operation performed at a hot temperature, the newly saved information in the middle track 30 may interfere with previously written adjacent tracks 22. Hence, this may cause unrecoverable hard errors when attempts are made to read the adjacent tracks 22 at a later time.
On the other hand, as shown in FIG. 2C, the width of the magnetic data bits in the middle track 32 were recorded at a cooler temperature resulting in a track which may be too narrow to be successfully read back. For a write operation performed at a cold temperature, the magnetic storage media may be so poorly written that the track cannot be properly read back. This may cause an unrecoverable read error when one attempts to read the data in the track at a later time.
Hence, a write operation to a magnetic disk works best when the device ambient temperature is within its normal operating temperature range. Conversely, a recording to a particular track performed at a temperature remote from the normal operating temperature may result in unrecoverable hard errors in a subsequent read operation attempted at the track or tracks adjacent to it. Data written to the track or in the adjacent tracks may never be properly read back. Therefore, it is desirable that the magnetic storage device ambient temperature be monitored before saving the data to the storage media and that data saved on the media be verified before completing the operation.
One object of the present invention is to provide a method and apparatus to insure that data saved onto a magnetic storage device are properly saved for future retrieval.
Another object of the present invention is to provide a method and apparatus to verify that data to be saved on a target track of a magnetic storage device are saved when the ambient temperature of the storage device is colder than normal operating temperature.
Yet another object of the present invention is to provide a method and apparatus to insure that data saved on a magnetic storage device when the ambient temperature of the storage device is within a predetermined range are verified before the save operation is complete.
One other object of the present invention is to provide a method and apparatus to insure that data in a tracks adjacent to a target track are unaffected by a write operation to the device when the device ambient temperature is warmer than normal operating temperature.
Briefly, the preferred embodiment includes a method for storing data on a target track of a recordable medium in a storage device via a magnetic head therein, said storage device has an operating parameter having an operational range with one extreme at which the writing of data to said device is prohibited. A first threshold within said range is defined and proximate said first extreme and delimits a first operational subrange. The method includes the steps of: monitoring said operating parameter; and determining whether the monitored parameter lies within said first subrange and if so, performing a first predetermined operation to compensate for deleterious effects on data storage caused thereby.
Another embodiment comprises a computer program product embodying a program of instructions executable by a machine to perform method steps for storing data on a target track of a recordable medium in a storage device via a magnetic write head. The storage device has an operating parameter having an operational range with one extreme at which the writing of data to said device is prohibited. A first threshold within said range is defined and proximate said first extreme and delimits a first operational subrange. The computer program product is operative to execute a method comprising the steps of: monitoring said operating parameter; and determining whether the monitored parameter lies within said first subrange and if so, performing a first predetermined operation to compensate for deleterious effects on data storage caused thereby.
Yet another embodiment includes a disk drive system having a magnetic storage medium for storing data in a storage device, wherein the head and storage medium are packaged in an enclosure. The system includes a controller for interfacing with an external system and controlling operation of the system; an actuator driver electrically coupled to said controller for positioning said head and writing data to said media; and a thermal sensor electrically coupled to said controller for monitoring the enclosure temperature so that a predetermined operation may be executed to compensate the storing operation if the enclosure temperature falls within a predetermined range.
An advantage of the present invention is that it insures that data saved onto a magnetic storage device are properly saved for future retrieval.
Another advantage of the present invention is that it provides a method and apparatus to insure that data to be saved onto a magnetic storage device are correctly saved when the ambient temperature of the storage device is within a predetermined range.
Yet another advantage of the present invention is that it provides a method and apparatus to verify that data saved on a magnetic storage device when the ambient temperature of the storage device is colder than normal operating temperature are retrievable before completing the save operation.
One other advantage of the present invention is that it provides a method and apparatus to insure that data in a track adjacent to a target track of a storage device are unaffected by a write operation to the device when the device ambient temperature is warmer than normal operating temperature.
The foregoing and other objects, features and advantages of the invention will be apparent from the following detailed description of the preferred embodiment which makes reference to the drawings.